Since I ride a hybrid outside and also do spin classes, I'm of a different opinion. Yes, constantly spinning the pedals indoors can be boring. You need some stimulation and that's where a subscription service may be the ticket.

Myself, I use a Pro-Form Studio Cycle that you can use with an iFit subscription. They have a lot of studio classes and rides that use Google maps to map the incline. The bike is automatically adjusted for gear and incline.

That said, there is a drawback to the bike that I own. The flywheel is only 14 pounds, which makes for choppy out of the saddle cadence when you use lighter resistance. It's easy for the flywheel to get ahead of the pedal cadence. If you do go the spin bike type of cycle route, look for one with a heavier flywheel for more fluid out of saddle riding.

Or, you could go the trainer route with a subscription to a service like Zwift. I like the Zwift idea, because you ride with and against others riders from around the world. It's most efficient if your bike/trainer has a good speed/cadence and power meter, especially the power meter. I tried using Zwift while on rollers with only a speed/cadence meter and it didn't accurately depict my output.